The GIS approach to evaporite-karst geohazards in Great Britain |
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| Authors: | A H Cooper |
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| Institution: | (1) British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK |
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| Abstract: | Evaporite karst in Great Britain has formed in Permian and Triassic gypsum, and in Triassic salt. Active dissolution of these
deposits can occur on a human rather than a geological timescale causing subsidence and building damage. The British Geological
Survey has taken two approaches towards understanding and advising on hazards caused by dissolution of these soluble rocks.
At a detailed level, a national database and GIS of karstic features is being populated. Information gathered includes dolines,
springs, stream sinks, caves and building damage. At a national level, the soluble rocks in Great Britain have been identified
and digital-map polygon information relating to them was extracted from the British 1:50,000-scale digital geological map.
These areas have been assessed, and in places their margins extended to include some overlying rocks where subsidence features
are known to penetrate upwards through the overlying sequence. The national areas have then been assessed using detailed local
information to assign a susceptibility rating from A (extremely low) to E (high), depending on the nature and regularity of
the subsidence events that occur. This national zonation of the soluble rocks can be used for planning, construction and in
the insurance businesses. This has proved useful for assessing the potential stability of linear routes, such as roads and
pipelines or for other important structures such as bridges and buildings. The information can also be used to delineate zones
of karstic groundwater flow. |
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| Keywords: | Evaporite Karst Subsidence GIS Hazard assessment |
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